Diffusion tensor imaging can measure the microstructural integrity and orientational structure of nerve tissue. Computational tools to extract microstructural information from DTI will enhance insight into neuroanatomy, neuropathology, and neuropsychiatric disorders. We propose to develop statistical tools to test group-level hypotheses on white matter histoarchitecture based on diffusion imaging. We will extend analytic and statistical tools developed for scalar data, to orientational diffusion data, leading to improved registration, segmentation, and analysis of tissue microstructure.